Free/Busy and Out of Office (OOO) Issues When Migrating from Exchange 2007 to Exchange 2010

I'm in the process of migrating from Exchange 2007 to Exchange 2010. (Wait, was this post written in 2016? Yes, I know. There are extenuating circumstances.) Instead of configuring lots and lots of servers to send email to the IP of the new Exchange 2010 server, I decided to swap IPs between the Exchange 2007 and 2010 server.

I went through and adjusted the URLs under all the Client Access categories: Outlook Web App, Exchange Control Panel, Exchange ActiveSync, etc. After making the changes I ran into two issues:

1. Issue: Exchange 2007 wasn't able to find itself via DNS.
   Fix: Turns out the person who built it put in a host file and hard coded the IP in that.
   Here's where to look for that:
   C:\Windows\System32\drivers\etc\hosts
2. Issue: Free/Busy information wasn't working for mailboxes on the Exchange 2007 server and Out of Office messages couldn't be set.
   Fix: There are URLs for the Web Services Virtual Directory that need to be updated but are not available (as far as I know) via the Exchange Management GUI.
1. I opened Exchange Management Shell
2. I ran this command to see the URLs assigned to each EWS.
   Get-WebServicesVirtualDirectory | select Identity, *url* | fl
   
   Identity             : Exch07\EWS (Default Web Site)
   InternalNLBBypassUrl : https://Exch07.my.biz/ews/exchange.asmx
   InternalUrl          : https://mail.my.biz/ews/exchange.asmx
   ExternalUrl          : https://mail.my.biz/ews/exchange.asmx
   
   Identity             : Exch10\EWS (Default Web Site)
   InternalNLBBypassUrl : https://Exch10.my.biz/ews/exchange.asmx
   InternalUrl          : https://Exch10.my.biz/EWS/Exchange.asmx
   ExternalUrl          : https://mail.my.biz/ews/exchange.asmx
3. Clearly mail.my.biz isn't going to work for two different servers. I needed to fix the internal URL and the external URL on my old 2007 server.
   
   Set-WebServicesVirtualDirectory –Identity “Exch07\EWS (Default Web Site)” –InternalUrl: https://Exch07.my.biz/ews/exchange.asmx
   
   Set-WebServicesVirtualDirectory –Identity “Exch07\EWS (Default Web Site)” –ExternalUrl: https://Exch07.my.biz/ews/exchange.asmx
   
   NOTE: You need the quotes and the whole string from the Identity field.
4. Then I restarted IIS on my Exchange 2007 server.
   It took a few minutes but the Free/Busy information started to populate and my ability to set Out of Office responses came back.